The present invention relates to aqueous polyurethane (PU) dispersion, and its production method and use, especially a non-fluoro, hydrophobic aqueous PU dispersion, and its production method and use.
Nowadays, the public places importance on outdoor activities, sports and work out. Regarding the dressing while doing exercise, the requirements for a functional dress are light, convenient and comfortable. Hence, this kind of functional dressing becomes the main business of the development. Generally, an outdoor dressing for user to feel comfortable usually requires a water-repellent surface, i.e. its materials have hydrophobic properties, and a property for releasing the moisture from human body at the same time, i.e. the fabric having a breathable function (moisture permeation and sweat release). This kind of product is needed in the current market.
The fabric having a function of moisture permeation and sweat release, which has been sold in market, uses the fabric which is fluoro-containing resin processed, i.e. fluoro-containing acrylic resin or PTFE (polytetrafluoroethylene) attached film. However, these materials already reach its limitation of water-repellent fabric in the aspect of resistance. In addition, no matter using fluoro containing resin or PTFE attached film as material for water-repellent treatment, these materials all have C8-fluoro compounds, PFOA (perfluoro-octanoic acid) or PFOS (perfluoro-octanesulfonic acid) salt and the like. These compounds are certified causing carcinogenesis. Hence, the water repellent having C8-fluoro compounds is eliminated gradually, and will be prohibited from 2015. Although there are low carbon (such as C6 or C4) fluoro-compounds used in market as fluoro-containing water repellent, in order to achieve to an expected water-repellent efficacy, the usage of low carbon fluoro-containing compounds require a higher amount than C8-fluoro-compounds do. This situation is expected to cause an impact to environment, especially the accumulation in alive organism, and further may cause the defects for considering the damage of ecological environment of earth.
In addition, the resin used in resin having fluoro-containing nowadays is acrylic-based resin mainly. When applying it to the coating process, this kind of resin cannot process the following cross-linking reaction. Hence, the processed products of resin having fluoro-content cannot maintain long-term efficacy of water repellent, and this is a problem which the fabric for treating water repellent needs to be dealt with. However, if the method of attached film is carried out, it is necessary for using specific extended PTFE film materials, specific dispensing glue and the facility for attaching film to carry out the process of attaching film for water-repellent fiber. Regarding the cleaning in aspect of customers, it requires specific professional method to clean it and that would be another inconvenience.
Generally, the water-repellent fabric in the market would have the following defects:
1. The bad hand-feel: Using the coating of water repellent having acrylic resin fluoro or PTFE attached film on the surface of fiber causes the stiff feeling when touching the fabric.
2. The poor washing durability: After the process of water-repellent coating, the known water-repellent fabric is only covered by the water repellent on its surface, instead of polymeric inter-penetrating networks (IPN) anchoring in fabric and forming between fabric yarns. Hence, after multiple times of use, it is easy to damage the fabric due to rubbing and washing, further to decrease the water-repellent function. The fabric has the durability decrease.
3. Poor Breathability: The processes material, such as water repellent, is covered on the surface of fabric by the coverage method. Due to overdose of resin coating on, the excess amount of resin plugs the fabric and decreases the original air permeability of fabric. The fabric has the defect on breathability.
4. The cost of protecting environment is too high: In the known knowledge, no matter using the method of coating or attached film, it requires a fluoro-containing polymer that can cause pollution loading, bio-toxicity and the accumulation in alive organism to environment. The fabric has the defect that cause damage to ecology of earth.
To sum up, it is necessary to develop a water repellent having non-fluoro compounds which is valuable and the water repellent needs to be improved urgently.